The Lost World or the Tepuys of Venezuela and Insects there

It is after the exploration of Im Thurn in 1884 (one year after the explosion of Krakatau in Indonesia and the famous tsunami over Indonesian islands) that Sir Arthur Conan Doyle wrote that fascinating science-fiction novel "The Lost World". In that the famous professor Challenger, surrounded by colleagues and journalists, discovered the dinosaurs, the pterodactyles, and the ape-men, without forgetting the saber-tooth tigers, and the plesiosaurs. During their expedition, the explorers even dined on a roasted iguanodon.

The forgotten plateaus were populated by the fertile imagination of the author with what we used to call "prehistory" beings, or more exactly Mesozoic animals with, however, several compromises with the truth; we mean here the facts of Palaeontology. At the end of Conan Doyle's book, one pterodactyle was brought back to London with a lot of difficulty, fed during the trip with rotten fishes. It escaped during a conference at the Royal Society from its basket, and flew away to the sky under the eyes of the scientists dumbfounded. Several films and TV shows reproduced the adventures of Professor Challenger in the Lost World.

Conan Doyle very probably was basing his novel on the Mount Roraima, in the SE of Venezuela, but some people consider his story as on Serra Ricardo Franco, in Brazil, near the Bolivian border. It is evident that those very old environs from the Palaeozoic remained unchanged during the Mesozoic. That it seems encouraged the fertile imagination of some writers and even of some scientists. What was there over those mountains, isolated, inaccessible, with vertical walls and sometimes raised over 3000 m above the Amazonian forest? This question has haunted human mind.

Those dramatically isolated mountains in the middle of the jungle were named tepuys (Spanish plural tepuyes) in Spanish, in English tepuy, tepuys, borrowed from the Indian local language, and derived from the Carib linguistic stock. A tepuy signifies a montain, normally with a truncate summit, that is a table mountain. There are tabular sandstone formations (Steyermark, 1987), also referred as cerros in Venezuela or serras in Brazil. They extend over an area of approximately 1,200,000 km2 in Venezuela, south of the Orinoco river, with also peripheral areas in western Guyana, southeastern Colombia, northern Brazil (Neblina) and a bit of Surinam. In Venezuela, there are hundreds of sandstone elevations but the prominent ones, the tepuys, are numbered around 50 or a little more. The Pico da Neblina, between Venezuela and Brazil reaches 3014 m, but most of the summits range between 1000-1300 to 2500 m (Steyermark, 1987; Jolivet 1991, 1993).

Many expeditions have been organized, generally annually during the only acceptable month with the minimum of rain, on the Venezuelan side of the main tepuyes. Recently, the Brazilians explored their side of the Neblina, but, due to political reasons, there is a tendency to stop periodically the expeditions in Venezuela. The National Geographic Society and the Missouri Botanical Garden contributed to the expeditions and to the knowledge, mostly of the original flora growing on those tepuys. In addition, the expeditions found original birds, specialized insects, some mammals like the tapirs, the pumas, black reptiles or frogs, homochromous with the black rocks, but definitely no dinosaurs, no pterodactyles, and no Mesozoic monsters. The flora, however is rich, endemic, and there is even an endemic plant family.

The flora seems very old but not really archaic, except perhaps for the Heliamphora, for instance, probable ancestors of North American Sarracenia and Darlingtonia. Working conditions there are difficult: repeated and violent storms, incessant rain, plant chaos with no paths and no way to walk, and strong winds. The helicopter has solved many problems. Thanks to it; people can go over those vertical cliffs and return safely. When PJ was collecting near the Auyan-Tepuy, a helicopter was daily transporting up and down Japanese film makers. Only Roraima, at the SE of Venezuela, is relatively accessible by foot, but the last steps are rather perilous. Those summits have much in common and some insects or plants are closely related. The endemism in tepuys is directly related to the altitude and to the superficy of the top. Small rises have only the flora of the surroundings.

Many books have been written on the tepuys, specially notable is the one by Charles Brewer, an odonatologist, a botanist and a great explorer. Klaus Jaffe, an entomologist and a professor at the Simon Bolivar University in Caracas studies the ants, which are very close systematically to a lowland species. Steyermark and his disciples studied mostly the flowering plants.

Old or modern flora have evolved there in a way somewhat similar to as in any insular area. Endemism is remarkable and the Lost World is rich in strange forms. Besides the archaic Sarraceniaceae, there are the Brocchinia (Bromeliaceae), the only protocarnivorous plants of the family, related to Catopsis, epiphytic in the Florida mangrove. There are two species of carnivorous Brocchinia on the tepuys and other species of Bromeliaceae are also there, but they don't catch insects. Peat-bogs with Brocchinia and Heliamphora remind one of the populations of Darlingtonia and Sarracenia in the west and east coasts in the USA.

The tepuys are generally abrupt, vertical cliffs, often impossible to climb. Those sandstone massifs were carved during past centuries by the Orenoque and Amazon tributaries. Don't forget that this area has been submitted to marine transgressions, and that, from 1.2 millions of km2 of area, only 200,000 survived the erosion in the form of sandstone mountains. Only a few, however, are high enough to be of a botanical interest.

Continental sediments were deposited on the Guyana shield, equivalent to the Brazilian shield, probably during the upper Jurassic or the Cretaceous or sometime much before. Those deposits were not uniform. According to some authors, those sandstones are similar to the central and meridional Brazilian deposits. Then the plateau has been gradually broken, and those cuts have been the result of a slow elevation, together with climatic changes, mostly an increasing rainfall and probably temporary floods. Tate, quoting Auyan-Tepuy in Venezuela, thinks that the elevation may still be going on.

Tepuys sandstones are not datable. No fossils have been found and all pollen analyses, spores, sponge spicules, found, are doubtful, and may be the result of contaminations. According to Snelling, these sandstones were formed during Triassic or even far back in the Precambrian. Really, the tepuys are made of stratified sandstones, quartzites, jasps, shales, conglomerats, and pebbles, with some inclusions of eruptive material. Also there have been found inclusions of mica and dolerite, and the dolerites have been dated as 1.7 billion year old.

A great part of that sandstone cover has been eroded and carried over as sand along the sides of the rise. The rocks of the base have been exposed on all sides and mass of fallen earth and stones are visible around. The remains of those formations represent the mountains themselves or the sandstone plateaus. On the summits, flat or curved, the soil consists mainly in a layer of white or reddish sand mixed with a bit of humus. The rocks on the top are often black, due to lichens. Amphibians and reptiles on the top tend to adopt the black colour. Vegetation there is as on an open savannah, with humid depressions forming peatbogs or rockpools. Some tepuys are hollow, with deep caves and caverns.

The climate on the top shows a short dry season. It rains 270 days a year, and storms and fog are frequent. The wind is always very strong. Temperature varies from 1°C to 25°C.

The altitudes of the high tepuys vary from 1200 m (Yapacana, Antana) to 3014 m (Neblina). Floral density and endemicity vary in function of surface, orientation, humidity, and topography, but many species are common to the all mountains. Certain species, as Drosera roraimae, are found everywhere.

While Neblina, Sipapo, Duida, Marahuaca and Guanay show unequal summits, Roraima, Ptaritepuy, and Chimanta have flat and equal summits. That could be due to different tectonic movements.

It seems a bit premature to speak of tepuys vegetation before the finalization of the Flora of the Guyana Amazonia, which is actually in the making. Cerro de la Neblina, in itself, shows the biggest percentage of endemism (60%). Curiously, if we find many endemic species, there is practically no endemic family, with the exception of the Tepuianthaceae and also the genus Tepuianthus. The origin of that flora is very diverse and many species have migrated from the lowland forest to the summits. Other species come from the Andes or present Gondwanian affinities (African or Indo-malaysian). A great part of those plants are adapted to the biotope (according to Maguire: 75%). The endemism in general is a result of local differentiations, from a general flora, altitudinal or not, from tropical America, Mexico or Brazil. The botanical colonisation of the Guyana shield dates probably from the lower Cretaceous, but that presumption is hypothetical.

Rather curiously, this flora is largely xerophytic despite the high humidity and frequent bouts of fog. Perhaps the sun reverberation on the dry and fissured rocks of the summits is the main cause of this. Bizarre forms have evolved with sclerophyll, reduced, waxy, bright leaves, often in tufts or in rosette, such as the Neblinaria celliae, which reminds one of the arboreal Senecio of the Ruwenzori in central Africa. Those bushes reach a size of one meter and are special to the cerro of Neblina. They belong to the Theaceae family and show pink flowers on their top. Many of those sclerophyll plants are covered with a silky, greyish, white or brown down.

Specialists distinguish a low vegetation, practically similar to the neighbouring Amazonian forest, a vegetation of talus slope till 500 m altitude, with a mountain humid forest higher up, which show some relationships with Andean forests and a vegetation on the escarpments where naked rocks harbour specialized plants, such as Bromeliaceae (Brocchinia). On the vertical places, where water is running, there are certain species of Lenticulariaceae (Utricularia), carnivorous epiphytes, which grow also on the summits.

The vegetation on the summits is the most diversified. There are real forests of big and small trees (Bonnetia), epiphytes, savannah, crevices and acidic peatbog plants (pH 3 to 5). None among the epiphytic plants is endemic and the orchids are numerous, since it is the most important family over the tepuys.

Small tepuys, as the Ptari Tepuys, with its summit composed of naked rocks and savannah, has poor flora diversity, but the Sarisarinama, which shows a different topography with open cavities, has evidently an original flora. Also, on the Guyana side there existed hot and cold, humid and dry phases; the glaciations and the intervals must have influenced this flora, its repartition and its diversity. Isolation, edaphic conditions, and palaeocli-matology have been the main factors resulting in the floristic diversity of the tepuys.

We find on the summits myrmecophilic plants belonging to Cecropiace-ae (2 species of Cecropia and one species of Coussapoa) and to Melasto-mataceae (51 species of Clidemia, 2 species of Miconia and one species of Myrmedone and one species of Tococa). How many among those plants are still myrmecophilic at that altitude? It remains to be found. In the Andes, Cecropia loses their relations with A%teca ants around 2200 m. Cecropia santanderensis from the Andes of Merida and C. auyantepuiana and C. kavanayensis from the tepuys are myrmecophobic species, i.e. free from ants. Some species of Cecropia are also myrmecophobic in the Amazon plain, and some species in central Brazil, as C. hololeuca. C. santanderensis, for instance, still has hollow stems, prostoma, trichilia, signs of a former occupation by A%teca ants. C. hololeuca has lost all those characters, except the hollow stem.

It is very probable that Clidemia, Miconia and Myrmedone have lost the ants at this altitude. The question remains for the Tococa from the mountains. Have they retained their relations with ants in the ant-pouches or have they lost them? Among the Melastomataceae are found mostly ants of the genera Crematogaster, A%teca, Allomerus, Pheidole and Myrmelachista. It seems probable that some still survive there since the altitudes are relatively moderate.

On the tepuys, carnivorous plants are numerous and diverse. The genus Heliamphora, as we have said that already, is endemic on all the summits. All those plants are Sarraceniaceae, but their leaves are not completely fused. There exists a split through which runs and overflows the accumulated liquid. Certain species possess even a drainage hole situated under the split and discovered by Tate during his first climbing. Among Heliamphora, Brewer has described a sort of siphon made of special hairs above the drainage hole. We have the impression that everything is "foreseen" to prevent, under those torrential rains, the complete filling of the pitcher, which would stop the digestion of the captured preys. In the pitcher water, mosquitoes breed and even a leech is present and the digestion of preys is entirely bacterial. No digestive enzyme has been so far detected.

Other carnivorous plants on the tepuys are Drosera roraimae, common everywhere, several species of Utricularia (U. quelchi, U. humboldti, U. alpina, U. amethistina) which often grow as epiphytes, so humid are the surroundings, between the leaves of Brocchinia and Orectanthe. There is also a Genlisea, and two Bromeliaceae, Brocchinia reducta and B. hectioides. Those Brocchinia grow generally in peat bogs or in isolated habitats over the rocks. They always like acidic, sandy, humid soil and grow in full sunlight. Inside the Brocchinia pitchers, mosquitoes breed, and they are not digested with the rest of insects.

To summarize, as mentioned by Steyermark, all these plants are adapted in the tepuys to a combination of an acidic soil, black waters, heavy rains, intense sunny radiations, violent wind, frequent fog, and sudden changes of temperature. Some of the results of these influences is the arrangement of leaves in rosettes, which is a frequent adaptation in the tropics, and the pitcher shape.

Fauna over the tepuys is relatively poor, but is very original. Unfortunately, despite the many expeditions and the frequent collections, it has not been thoroughly studied, mostly for the insects. The exploration of the zoologist Tate, in 1926, is interesting, since it gave a good review of the fauna of Roraima. The birds were well studied by specialists, and Mayr and Phelps, in agreement with the botanists, admit that the tepuys have formed a minor centre of dissemination, which contains also several relics of types formerly more widely distributed. Speciation among birds of the area has been studied by Haffer.

On the summits hummingbirds and parrots are found, several small mammals (mice, Conolestes), and also big animals like tapirs and pumas. Some small black toads (e.g. Oreophrynella) are homochromous with the rocks, and are found sometimes inside Brocchinia pitchers.

The insect world is rich and diverse. In the first description of Roraima insects, in 1895, Waterhouse mentions a dytiscid, a lucanid, an elaterid and a cryptocephaline, all new to science. Tate mentions also various arach nids (some spiders live inside the pitchers of the carnivorous plants where they capture their preys), myriapods, Collembola, Odonata, Trichoptera, Psocoptera, Homoptera, Hemiptera, Thysanoptera, Lepidoptera, Coleoptera, Diptera, and Hymenoptera. Most of the main insect groups are represented there. There are also ants studied by Klaus Jaffe in Caracas.

It is the same Klaus Jaffe and one of his students (Issa and Jaffe, 1999) who discovered aquatic grasshoppers in the bottom of the rock pools on various summits of the tepuys, namely Hydrolutos roraimae and 3 more species. They belong to the family Anostostomatidae. Those insects are nocturnal and stay during the day at the bottom of rock pools entirely submerged. They feed on algae and stay under water for periods of more than 20 minutes each time. They rise up to catch air from time to time. They swim very well, but are very frail and cannot survive in captivity for more than 10 days. They have been collected on Auyantepuy, Roraima, Kukenam and Aracamuni, and there must be more species elsewhere. Let us summarise that on Cerro do Cipo in Brazil, there are in the bottom of rock pools, on the mountain, Dynastinae (Chalepidesfuliginosus), mimicking Dytiscidae, and feeding on detritus, aquatic plants and algae (Jolivet, 1993). They are preadapted to this aquatic life, due to having abundant hairs at the apex of elytra, stigmata invaginated below the general abdominal surface, fusiform body shape, and with air accumulation under the elytra. The lifestyle for the grasshopper is completely aberrant, and this suggests that in tepuys there is still a lot to be discovered.

Most of these insects are endemic in the tepuys, and many remain to be described. Most of the flea beetles, Alticinae, for instance, still remain undescribed, and also many other beetles. Since the expeditions are generally arranged during the better (dry) season, we see what remains of the insect fauna during the rest of the year. And still many of these summits have never been explored scientifically.

When we see what remarkable adaptations are shown by the plants to that hostile conditions, we can imagine what it can be with the insects in that humid, windy, hot and cold, sunny world, a world of extremes. A world, which lodges so many special, xerophytic, carnivorous, ultraspecialized plants should also have produced insects as specialized. Long expeditions are needed and it may be expected that many new visits by scientists will be organized in the near future.

Summit Escarpment

Summit Escarpment

Talus slope Escarpment Talus slope

Lowland Forest ■ Fig. 24.1. A typical tepuy in Venezuela.

Talus slope Escarpment Talus slope

Lowland Forest ■ Fig. 24.1. A typical tepuy in Venezuela.

— Fig. 24.2. Major tepuys of Venezuela (after Steyermark, 1987).

— Fig. 24.3. Lowlands around the tepuys (photo Jolivet).

— Fig. 24.4. A tepuy, view from the forest (photo Jolivet).

— Fig. 24.5. Auyan-tepuy in Venezuela. From there you can see Angel fall during good weather, the highest fall in the world (photo Jolivet).